Electrical stimulation to alleviate chronic pelvic pain

ABSTRACT

The disclosure describes a method and system for applying electrical stimulation to a genitofemoral nerve or a genital branch of a genitofemoral nerve of a patient. The system includes electrical stimulators that apply electrical stimulation for alleviation of pelvic pain. The system may apply electrical stimulation for pelvic pain in men or women. The electrical stimulators may comprise various types of electrodes such as cuff electrodes, electrode leads, and microstimulators implanted at various locations proximate to a single or both genitofemoral nerves and the genital branch of a single or both genitofemoral nerves of a patient. When implanted proximate to a genital nerve branch, the electrode may be implanted proximate to the genital nerve branch. In a male patient stimulation may be delivered proximate to the spermatic cord, which contains a portion of the genital nerve branch.

This application is a continuation of U.S. application Ser. No.11/413,621, filed Apr. 28, 2006, which is a continuation-in-part (CIP)of U.S. application Ser. No. 11/344,580, filed Jan. 31, 2006, the entirecontent of each of which is incorporated herein by reference.

TECHNICAL FIELD

The invention relates to medical devices and, more particularly, todevices for delivering neurostimulation therapy.

BACKGROUND

Pain in the pelvic region, including urogenital pain, may be caused by avariety of injuries or disorders in men and women. For example, chronictesticular pain (CTP), post vasectomy pain, genitofemoral neuralgia andother pain originating from the testicles, groin, or abdomen are commonreasons for referral to a urological specialist. The incidence ofpatients with CTP, also referred to as orchialgia, orchidynia, orchronic scrotal pain, is large and may be caused by on-goinginflammation of the testicle (orchitis) or epididymis (epdidymitis),trauma, tumors, hernia, torsion (twisting of the testicle), varicocele,hydrocele, spermatocele polyarteritis nodosa, and previous surgicalinterventions such as vasectomy and hernia surgery.

As an example, CTP or genitofemoral neuralgia may be attributed to nerveinjury, such as stretching of a nerve, electrocoagulation, stricturecaused by ligation, entrapment of the nerve in scar tissue, orirritation because of proximity to a zone of inflammation, duringinguinal herniorrhaphy. The pain experienced by the patient may beunilateral or bilateral, constant or intermittent, spontaneous orexacerbated by physical activities and pressure, and may remainlocalized in the scrotum or radiate to the groin, perineum, back, orlegs.

Typically, testicle removal and spermatic cord denervation proceduresare used to treat CTP. In spermatic cord denervation procedures, nervesin or adjacent to the spermatic cord, i.e., the genitofemoral nerve orsympathetic nerves, are severed or permanently removed. Such proceduresmay result in permanent and substantial pain relief regardless of theorigin of pain. However, severing or removing these nerves may result inloss of sensation in the testicle and/or scrotum, loss of thecremasteric reflex which may cause fertility issues, and even loss ofblood flow causing the testicle to die. Therapeutic nerve blocks mayalso be used to treat CTP, but generally only relieve pain temporarily.

In addition, women may experience various types of sources of pelvicpain. Sources of pain may include injury to nerves resulting fromsurgical procedures, non-surgical conditions, vulvodynia which can bevery debilitating but has no obvious source, and interstitial cystitis(painful bladder syndrome). Interstitial cystitis may be a source ofpelvic pain in both women and men. Surgical procedures that may injurenerves in the pelvic region may include urological operations in thepelvic area, gynecological surgery, and hysterectomy. Non-surgicalconditions which cause pain in women include adhesions, endometriosis,and pelvic congestion.

SUMMARY

In general, the invention is directed to techniques for applyingelectrical stimulation to a genitofemoral nerve or a genital nervebranch of the genitofemoral nerve of a patient via an implantableelectrical stimulation device to alleviate symptoms of chronic pelvicpain in men or women. Pelvic pain may include urogenital pain or otherforms of pelvic pain. The electrical stimulation may be applied to oneor both genitofemoral nerves. In addition, the electrical stimulationmay be applied directly to the genital branch of one or bothgenitofemoral nerves or, in the case of male patients, indirectly viathe spermatic cord which contains a portion of the genital nerve branch.

A system according to the invention may include one or more electricalstimulators that apply electrical stimulation to the genitofemoral nerveor the genital branch of the genitofemoral nerve, e.g., via thespermatic cord in a male patient, to alleviate chronic testicular pain(CTP) or other afflictions associated with pelvic pain, including painoriginating from the testicles, groin, or abdomen, such as postvasectomy pain and genitofemoral neuralgia. In female patients, anelectrical stimulator delivers the stimulation to the genitofemoralnerve or genital nerve branch to alleviate other types of pelvic painsuch as vulvodynia, interstitial cystitis, post-operative pain,adhesions, endometriosis or pelvic congestion.

The electrical stimulators may comprise various types of electrodes suchas cuff electrodes, electrode leads, and/or microstimulators implantedat various locations proximate to one or both of the genitofemoralnerves of a patient or the genital branch of one or both genitofemoralnerves. The electrical stimulators may alternatively or additionally beimplanted proximate to the genital branch of one or both genitofemoralnerves of a patient, e.g., directly or via the spermatic cord. In thismanner, stimulation may be applied uni-laterally (to one cord or branch)or bi-laterally (to both cords or branches).

In some embodiments, electrical stimulation electrodes may be coupled toan implantable stimulation device implanted within a subcutaneous pocketin the abdomen or buttock of the patient or, alternatively, the scrotumof the patient. The electrical stimulation electrodes may be coupled tothe implantable medical device via standard implantable electrode leads.Alternatively, leadless microstimulators may be positioned adjacent thetarget cords or nerves. In this case, the leadless microstimulators maybe capable of wireless communication with other implantable medicaldevices, an external programmer, or both.

For male patients, stimulation electrodes or leadless microstimulatorsmay be implanted using well known surgical procedures for exposing thespermatic cord, e.g., inguinal incision as used for spermatic corddenervation or hernia repair. Systems including such electrodes ormicrostimulators and employing the techniques described in thisdisclosure may substantially reduce or eliminate chronic pelvic pain,including urogenital pain such as CTP, without loss of sensation in thetesticles and/or scrotum or loss of the cremasteric reflex as is commonwith testicle removal and spermatic cord denervation procedures.

Systems according to the invention may include an external programmerthat programs the electrical stimulators to apply electrical stimulationto a genitofemoral nerve or genital nerve branch, e.g., directly or viaa respective spermatic cord. During stimulation, a clinician or patientmay operate the external programmer to adjust stimulation parameters,such as amplitude, pulse width, pulse rate, and electrode polarities. Insome cases, a patient may use the programmer to deliver stimulation ondemand, e.g., when the patient experiences discomfort. Additionally oralternatively, the implantable stimulation device may store stimulationprograms and schedules. In this manner, the electrical stimulation canbe delivered according to preprogrammed stimulation parameters andschedules, if desired.

In one embodiment, the invention provides a method comprising applyingelectrical stimulation to a genital nerve branch of a genitofemoralnerve of a patient via an implanted electrical stimulation device.

In another embodiment, the invention provides a system comprising animplantable electrical stimulation device that generates electricalstimulation selected to alleviate pelvic pain, and an electrode coupledto the electrical stimulation device at a position adjacent to a genitalnerve branch of a genitofemoral nerve a patient.

In a further embodiment, the invention provides a method comprisingapplying electrical stimulation to at least a portion of a genitofemoralnerve of a patient via an implanted electrical stimulation device.

In another embodiment, the invention provides a system comprising animplantable electrical stimulation device that generates electricalstimulation selected to alleviate pelvic pain, and an electrode coupledto the electrical stimulation device at a position adjacent to agenitofemoral nerve of a patient.

In various embodiments, the invention may provide one or moreadvantages. For example, applying electrical stimulation to agenitofemoral nerve of a patient may substantially reduce or eliminatepelvic pain such as that caused by chronic testicular pain (CTP), postvasectomy pain, genitofemoral neuralgia, and other conditions that causelong term pain in the testicles, groin, or abdomen, as well as otherforms of pelvic pain experienced by female patients.

Testicle removal and spermatic cord denervation procedures that severnerves in or adjacent to the spermatic cord, i.e., a genital branch ofthe genitofemoral nerve, ilioinguinal nerve, or sympathetic nerves,often result in unwanted side effects including loss of sensation in thetesticles and/or scrotum and loss of the cremasteric reflex which maycause fertility issues. Therapeutic nerve blocks typically only relievepain temporarily. In contrast, delivery of electrical stimulation to oneor both genital nerve branches, either directly or via the respectivespermatic cords, may provide permanent or long-lived effective therapyfor many patients with fewer or no unwanted side effects.

In addition, for male patients, electrical stimulators may be implantedproximate to the spermatic cord using well known surgical procedures forexposing the spermatic cord, e.g., inguinal incision as used forspermatic cord denervation or hernia repair, providing ease ofdeployment by experienced surgeons or other caregivers.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating an example system thatincludes an implantable stimulation device for applying electricalstimulation to a genital nerve branch of a patient for alleviation ofpelvic pain from a front view of a male patient.

FIG. 2 is a schematic diagram further illustrating the example system ofFIG. 1 from a side view of a male patient.

FIGS. 3A-C are schematic diagrams illustrating an example cuff electrodeuseful in the system of FIGS. 1 and 2.

FIG. 4 is a block diagram illustrating an example implantablestimulation device for applying electrical stimulation to the genitalnerve branch of a patient.

FIG. 5 is a block diagram illustrating an example clinician programmerthat allows a clinician to program electrical stimulation therapy for apatient.

FIG. 6 is a block diagram illustrating an example patient programmerthat allows a patient to control delivery of electrical stimulation.

FIG. 7 is a schematic diagram illustrating another example systemincluding two different types of electrical stimulators for applyingelectrical stimulation to a genital nerve branch of a patient from afront view of a male patient.

FIG. 8 is a schematic diagram further illustrating the example system ofFIG. 7 from a side view of a male patient.

FIGS. 9A and 9B are schematic diagrams illustrating an example electrodelead of FIGS. 7 and 8.

FIG. 10 is a schematic diagram further illustrating the example systemof FIG. 7.

FIGS. 11A-C are schematic diagrams illustrating an example leadlessmicrostimulator suitable for use in the system of FIGS. 7 and 8.

FIG. 12 is a side cross-sectional view of a leadless electricalmicrostimulator implanted within the spermatic cord.

FIG. 13 is a schematic diagram illustrating implantation of a leadlessmicrostimulator within the spermatic cord or tissue adjacent thespermatic cord.

FIG. 14 is a functional block diagram illustrating various components ofthe leadless microstimulator of FIG. 12.

FIG. 15 is a flow chart illustrating a technique for applying electricalstimulation to a spermatic cord of a patient for alleviation of pelvicpain.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram illustrating an example system 2 thatincludes an implantable medical device (IMD) 28 in the form of anelectrical stimulator that applies electrical stimulation to one or bothgenitofemoral nerves or the genital branch of one or both genitofemoralnerves, either directly or via spermatic cords 14 and 15 of a patient10. In FIG. 1, system 2 is illustrated from a front view perspective ofpatient 10. Of course, application of stimulation to spermatic cords 14,15 applies only in the case of male patients. Although the invention maybe generally applicable to treat pelvic pain in both men and women,application of the invention to men will be described throughout thisdisclosure for purposes of illustration. Throughout the figuresaccompanying this disclosure, various anatomical features of patient 12and structural features of system 2 are illustrated conceptually forease of illustration. Accordingly, the figures may not necessarilypresent appropriate scales and proportions of such anatomical features.Rather, the drawings are indicated as a conceptual rendering of suchfeatures to aid in the understanding of pertinent embodiments of theinvention.

In the example of FIG. 1, IMD 28 applies electrical stimulation topatient 10 for alleviation of chronic testicular pain (CTP), postvasectomy pain, genitofemoral neuralgia, and other conditions that causelong term (chronic) pain in the testicles (in a male patient), groin, orabdomen. CTP may be caused by on-going inflammation of the testicle(orchitis) or epididymis (epdidymitis), trauma, tumors, hernia, torsion(twisting of the testicle), varicocele, hydrocele, spermatocelepolyarteritis nodosa, and previous surgical interventions such asvasectomy and hernia surgery. As an example, CTP or genitofemoralneuralgia may be attributed to nerve injury, such as stretching of anerve, electrocoagulation, stricture caused by ligation, entrapment ofthe nerve in scar tissue, or irritation because of proximity to a zoneof inflammation, during inguinal herniorrhaphy. In particular, damage tothe genitofemoral nerve and, more particularly, the genital branch ofthe genitofemoral nerve may cause a patient to experience pain in thetesticles or associated scrotal area. Stimulation parameters such asamplitude, pulse width and pulse rate may be selected as appropriate toalleviate pain for the particular patient 10.

In additional embodiments, IMD 28 applies electrical stimulation to afemale patient (not shown) for alleviation of pelvic pain such as,urogenital pain. Examples of pain include pain resulting from surgicalprocedures, non-surgical procedures, vulvodynia, and interstitialcystitis (painful bladder syndrome). Nerve injury may be caused byvarious surgical procedures including urological operations in thepelvic area, gynecological surgery, and hysterectomy. Non-surgicalcondition which cause pain in women include adhesions, endometriosis,and pelvic congestion. For male or female patients, the pain may beidiopathic in origin. Applying electrical stimulation to thegenitofemoral nerve or genital branch of the genitofemoral nerve inaccordance with selected stimulation parameters may alleviate painexperienced by female patients.

FIG. 1 illustrates genital branches 22, 23 and femoral branches 24, 25of genitofemoral nerves 20, 21, respectively. Generally, for a malepatient, IMD 28 delivers electrical stimulation to spermatic cords 14and 15 via electrodes which may be coupled to IMD 28 by one or moreleads to block pain signals from testicles 12 and 13 and the associatedscrotal area 11 from reaching the central nervous system (CNS). As shownin the illustrated example of FIG. 1, the electrodes may be configuredto at least partially engage a portion of the genital nerve branch orspermatic cord. However, the invention is not so limited. Rather, theinvention also includes embodiments in which electrodes may be implantedproximate to genitofemoral nerves 20, 21, i.e., above the branch pointof genital nerve branches 22, 23, respectively. In the illustratedexample of FIG. 1, a dotted circle indicates an example stimulation sitealong genitofemoral nerve 20, 21.

Further, the invention includes embodiments in which an electrode isimplanted proximate to at least one of genitofemoral nerve 20,genitofemoral nerve 21, genital nerve branch 22, genital nerve branch23, spermatic cord 14, and spermatic cord 15. For example, electrodesmay be implanted proximate to genitofemoral nerve 20 and proximate togenital nerve branch 22. In another example, electrodes may be implantedproximate to genitofemoral nerve 20 and proximate to spermatic cord 14.In yet another example, electrodes may be implanted proximate to genitalnerve branch 22 and proximate to spermatic cord 14. The inventionfurther includes embodiments in which electrodes are implantedbi-laterally in any combination. Such embodiments are included withoutexhaustively listing all possible combinations. Accordingly, thepositions of electrodes 16 and 17 in FIG. 1 are merely exemplary.

The pain experienced by the patient may be unilateral or bilateral,constant or intermittent, spontaneous or exacerbated by physicalactivities and pressure, and may remain localized or radiate outward. Ina male patient, for example, testicular pain may remain localized in thescrotum or radiate to the groin, perineum, back, or legs. Deliveringelectrical stimulation causes parasthesia in testicles 12 and 13 andassociated scrotal region 11 based on the position of the electrodes.The number and position of the leads is largely dependent on the painperceived by the patient and the type of electrical stimulationdelivered to treat the pain. Additionally, the leads coupled to IMD 28may include various types of electrodes depending on the type ofstimulation delivered and the location of the lead.

In the illustrated example, IMD 28 is coupled to leads 18 and 19. Leads18, 19 may carry conventional ring electrodes, a paddle electrode array,or other types of electrodes. In the example of FIG. 1, leads 18 and 19each include a cuff electrode, i.e., cuff electrodes 16 and 17, whichdelivers electrical stimulation therapy to spermatic cords 14 and 15,respectively. A cuff electrode includes a cuff-like fixation structureand one or more electrodes carried by the fixation structure. In theexample of FIG. 1, leads 18 and 19 are implanted at different locationsalong spermatic cords 14 and 15, respectively. As a result, patient 10may experience parasthesia in different areas on each side of his bodyin response to electrical stimulation delivered by electrodes 16 and 17.

Again, the invention is not limited to embodiments in which IMD 28 iscoupled to cuff electrodes. Instead, IMD 28 may be coupled to any numberand any type of electrodes, such as conventional ring electrode leads,paddle electrode leads, and other electrodes suitable for deliveringelectrical stimulation to the spermatic cord. In addition, in somecases, leadless stimulators may be used. Further, the invention is notlimited to embodiments that deliver electrical stimulation to a specificarea of the spermatic cord.

As an example, FIG. 7 illustrates another example system in which an IMDis coupled to an electrode lead having electrodes displaced on thedistal end of the lead to stimulate a genital nerve branch of a patient,either directly or via a spermatic cord. FIG. 7 also illustrates aleadless microstimulator implanted within the fascia of a spermaticcord. In this case, an IMD or external programmer may wirelessly controlthe leadless microstimulator to deliver electrical stimulation to thefascia of the spermatic cord. In addition, although not illustrated, anIMD may also be coupled to an electrode suitable for applying electricalstimulation to the genitofemoral nerve.

With further reference to FIG. 1, IMD 28 may be coupled to deliverelectrical stimulation energy to spermatic cords 14, 15 via cuffelectrodes 16, 17, respectively. Cuff electrodes 16 and 17 each maycomprise a rigid cuff electrode, a self-sizing spiral cuff electrode, ahalf cuff electrode, a helical electrode, a chambered electrode, orother types of cuff electrodes that are shaped, sized and otherwiseconfigured to at least partially wrap around a spermatic cord. The cuffelectrode may be sized and shaped to at least partially enclose thespermatic cord and promote electrical coupling pressure between theelectrode and the fascia of the spermatic cord. The cuff electrodes 16,17 may each include a single electrode or multiple electrodes. Forexample, a cuff electrode 16, 17 may include a bipolar or multipolararrangement of electrodes or a unipolar electrode that is referenced tothe electrical potential of an active can electrode carried by IMD 28.

IMD 28 includes electrical stimulation pulse generator circuitry anddelivers electrical stimulation in the form of electrical pulses inaccordance with stored stimulation parameters, e.g., electrode polarity,pulse amplitudes, pulse widths, and pulse rates. By way of example, theelectrical stimulation may include stimulation pulses having pulsewidths between approximately 10 and 5000 microseconds, more preferablybetween approximately 100 and 1000 microseconds and still morepreferably between 180 and 450 microseconds. The stimulation pulses maydefine voltage amplitudes between approximately 0.1 and 50 volts, morepreferably between approximately 0.5 and 20 volts and still morepreferably between approximately 1 and 10 volts. The pulses may definefrequencies between approximately 0.5 and 500 hertz, more preferablybetween approximately 10 and 250 hertz and still more preferably betweenapproximately 50 and 150 hertz. The pulses may be alternating current(ac) pulses or direct current (dc) pulses, and may be mono-phasic,bi-phasic, or multi-phasic in various embodiments.

IMD 28 may drive electrodes 16 and 17 with the same or differentstimulation pulses or waveforms. In some embodiments, IMD 28 may causeelectrodes 16 and 17 to deliver electrical stimulation simultaneously,or in an interleaved or alternating fashion. For example, electrodes 16and 17 may deliver electrical stimulation with different pulse rates,duty cycles or scheduled times for delivery, which may result inalternating delivery of stimulation. Interleaved or alternating deliveryof stimulation may, for example, reduce the likelihood that neuralaccommodation or tolerance will impair the efficacy of the stimulation.Interleaved or alternating delivery of stimulation may also result inmore complete pain relief than would be possible through delivery ofstimulation via only one electrode or electrode array.

Leads 18 and 19 may be implanted proximate to spermatic cords 14 and 15,respectively. In the illustrated example, lead 18 is implanted proximateto spermatic cord 14 and lead 19 is implanted proximate to the genitalbranch 23 of genitofemoral nerve 21, but the invention is not limited assuch. Rather, lead 18 may be implanted at various locations alongspermatic cord 14, genital nerve branch 22, genitofemoral nerve 20, orsympathetic nerves (not shown). Spermatic cord 14 includes a lowerportion of the genital nerve branch 22 of the genitofemoral nerve 20.Similarly, lead 19 may be implanted at various locations along spermaticcords 15, genital nerve branches 23, genitofemoral nerves 21, orsympathetic nerves (not shown). The positions of leads 18 and 19 in FIG.1 are shown for purposes of illustration to show different possibleimplantation locations and associated target stimulation sites.Specifically, leads 18 and 19 illustrate two locations which may beparticularly advantageous for applying electrical stimulation, whichwill be described in detail below. However, IMD 28 may be coupled to asingle lead or a plurality of leads based on the perceived pain of thepatient and his response to electrical stimulation therapy.

In FIG. 1, spermatic cords 14 and 15, genitofemoral nerves 20 and 21,and genital branches 22, 23 and femoral branches 24, 25 of genitofemoralnerves 20 and 21 are illustrated. FIG. 1 also illustrates inguinalcanals 26 and 27. However, the genitofemoral nerve 20, 21 originatesfrom the L1 and L2 nerves in the lumbar region (lower back) at L1/L2. Asthe genitofemoral nerve 20, 21 passes through the lumbar region, itcrosses behind the ureter (not shown). Slightly posterior to and at avariable distance above the inguinal ligament (not shown), thegenitofemoral nerve 20, 21 divides into the genital branches 22, 23 andfemoral branches 24, 25. The genital branches 22, 23 cross thetransverses abdominus (not shown) and internal oblique muscles (notshown) and enter the respective inguinal canal 26, 27 through theinternal inguinal ring.

Within the inguinal canal 26, 27, the genital branch 22, 23 runs alongthe spermatic cord 14, 15, respectively. The spermatic cord includesvarious layers (not shown). These layers are the external spermaticfascia, cremasteric muscle and fascia, genitofemoral nerve, internalspermatic fascia, ductus deferens, lymph vessels, pampiniform plexus ofveins which become the testicular vein, and testicular artery. Morespecifically, as the structures within the spermatic cord pass throughthe transversalis fascia (not shown), they join with one of the layersof the spermatic cord, the internal spermatic fascia.

As the spermatic cord 14, 15 continues through the inguinal canal, itjoins with the cremasteric layer of muscle and fascia from the internaloblique muscle. These muscle fibers perform an important reflex, i.e.,the cremasteric reflex. When the cremasteric muscle contracts, thetesticle is pulled closer to the body. This reflex keeps the testiclesat the correct temperature, for example, by relaxing when the testiclesare too warm and contracting when the testicles are too cold. If thecremasteric reflex is absent or functions incorrectly, e.g., due todenervation or resection, the male may experience fertility relatedissues.

Finally, when the spermatic cord 14, 15 passes through the superficialring, it joins an external spermatic fascia layer derived from theaponeurosis of the external oblique. After the spermatic cord 14, 15traverses the inquinal canal 26, 27, it leads into the scrotum and tothe testes 12, 13 where the genital branch 22, 23 of the genitofemoralnerve innervates the testes 12, 13. Electrical stimulation may bedelivered via electrodes positioned proximate to the spermatic cordsuperior to a testicle and inferior to an inguinal canal of the patient,or positioned proximate to a genital branch of the genitofemoral nervesuperior to an inguinal canal and inferior to the genitofemoral nerve ofthe patient.

In the illustrated example, cuff electrode 16 is wrapped around theexternal fascia of spermatic cord 14 and connected to IMD 28 via lead 18and, optionally, a lead extension (not shown). The electricalstimulation applied by cuff electrode 16 stimulates the genital branch22 of genitofemoral nerve 20 through the fascia. The fascia protectsgenital nerve branch 22 within spermatic cord 14 from being in directcontact with the cuff electrode, thus avoiding adhesion. Adhesion may beundesirable because the nerve may become damaged as the patient moves orif the electrode is removed. Thus, it may be desirable to deliverelectrical stimulation to the spermatic cord by wrapping a cuffelectrode around the spermatic cord below the inguinal canal and abovethe attached testicle, as shown in FIG. 1 with respect to electrode 16.

Electrode 17, in the illustrated example, also comprises a cuffelectrode. More specifically, cuff electrode 17 is wrapped aroundgenital nerve branch 23 above inguinal canal 27 and below genitofemoralnerve 21. Because cuff electrode 17 is located higher (upstream in thecentral nervous system) from cuff electrode 16, patient 10 mayexperience parasthesia over a larger area, which may be advantageous insome instances. However, genital nerve branch 23 does not include anexternal fascia to serve as a protective layer in this region.Consequently, wrapping cuff electrode 17 around genital nerve branch 23may inherently have a greater risk of pinching or otherwise damaging thenerve, possibly reducing the long-term efficacy of the electricalstimulation. As a result, additional care may be necessary when wrappinga cuff electrode around the genital nerve branch above the inguinalcanal and below the genitofemoral nerve, as shown with respect toelectrode 17.

The positions of electrodes 16, 17 in FIG. 1 are for purposes ofillustration of different possible positions. In practice, one or bothelectrodes 16, 17 may be positioned above inguinal canal 27 and belowgenitofemoral nerve 21 to directly stimulate genital nerve branch 23.Alternatively, one or both electrodes 16, 17 may be positioned belowinguinal canal 27 and above testes 12, 13 to indirectly stimulategenital nerve branch 23 indirectly via spermatic cord 15. As discussedpreviously, electrodes may be positioned based on the pain perceived bythe patient and the type of electrical stimulation delivered to treatthe pain. In general, to treat pelvic pain such as CTP, electrodes maybe implanted proximate to the spermatic cord above or below the inguinalcanal to apply electrical stimulation to the genital branch of thegenitofemoral nerve or proximate to the genitofemoral nerve to applyelectrical stimulation to the genitofemoral nerve.

In general, it may be difficult to wrap a cuff electrode around thespermatic cord within the inguinal canal. Furthermore, it may not bedesirable to apply electrical stimulation to the spermatic cord withinthe inguinal canal because the spermatic cord joins the cremastericmuscle as it passes through the inguinal canal. Consequently,stimulating the spermatic cord within the inguinal canal may result inunwanted triggering of the cremasteric reflex.

Leads 18 and 19 are typically either surgically implanted or insertedpercutaneously. Leads 18 and 19 may be surgically implanted using wellknown surgical techniques. For example, the surgical procedure forexposing the spermatic cord is well defined, i.e., inguinal incision asused for spermatic cord denervation or hernia repair. A surgicalprocedure for genitofemoral neurectomy is described in detail in JudithA. Murovic et. al, “Surgical Management of 10 Genitofemoral Neuralgiasat the Louisiana State University Health Sciences Center,” Neurosurgery,Volume 56, Number 2, pages 298-303, February 2005. A procedure forspermatic cord denervation is described in detail in Laurence A. Levineet al., Microsurgical Denervation of the Spermatic Cord as PrimarySurgical Treatment of Chronic Orchialgia, The Journal of Urology, Vol.165, pages 1927-1929, June 2001. Prior to surgically implantingelectrodes, local nerve blocks may be performed using a nerve blockingagent to determine the precise nerve involved in the pain experienced bythe patient. If a spermatic nerve block ameliorates the patient's pain,a surgeon may conclude that electrical nerve stimulation is likely to beefficacious, and may proceed to surgically implant electrodes inaccordance with the invention. Alternatively, a clinician may stimulatethe patient using an insulated needle to determine the nerve involvedand the placement of an electrode. The diagnosis may also be made usingthe results of the patient history, physical examination, andpreoperative electromyography.

IMD 28 may be implanted at a site in patient 10 near spermatic cords 14and 15. The implantation site may be a subcutaneous location in the sideof the lower abdomen or the buttock. Alternatively, IMD 28 may beimplanted within the scrotum of the patient. In this case, IMD 28 may beminiaturized to allow IMD 28 to be implanted within the scrotum. In anycase, the surgeon may then tunnel a lead through tissue and subsequentlyconnect the lead to IMD 28, with or without a lead extension. IMD 28 maybe constructed with a biocompatible housing, such as titanium orstainless steel, much like a conventional neurostimulator such as thoseused for spinal cord stimulation or pelvic stimulation, e.g., for reliefof chronic pain, sexual dysfunction, or urinary or fecal incontinence.

External programmer 29 may control delivery of electrical stimulation byIMD 28. For example, in some embodiments, external programmer 28 maycomprise a clinician programmer or a patient programmer. A clinicianprogrammer may be a handheld computing device including a display, suchas an LCD or LED display, to display electrical stimulation parameters.A clinician programmer may also include a keypad, which may be used by auser to interact with the clinician programmer. In some embodiments, thedisplay may be a touch screen display, and a user may interact with theclinician programmer via the display. A user may also interact with theclinician programmer using peripheral pointing devices, such as a stylusor mouse. The keypad may take the form of an alphanumeric keypad or areduced set of keys associated with particular functions.

A clinician (not shown) may use the clinician programmer to programelectrical stimulation to be delivered to patient 10. In particular, theclinician may use the clinician programmer to select values for therapyparameters, such as pulse amplitude, pulse width, pulse rate, electrodepolarity and duty cycle, for one of or both electrodes 16 and 17. IMD 28may deliver the electrical stimulation according to programs, eachprogram including values for a plurality of such therapy parameters. Inthis manner, IMD 28 controls delivery of electrical stimulationaccording to preprogrammed stimulation programs and schedules.

When implemented as a patient programmer, external programmer 29 may bea handheld computing device. The patient programmer 26 may also includea display and a keypad to allow patient 10 to interact with the patientprogrammer. In some embodiments, the display may be a touch screendisplay, and patient 10 may interact with the patient programmer via thedisplay. Patient 10 may also interact with the patient programmer usingperipheral pointing devices, such as a stylus or mouse.

Patient 10 may use the patient programmer to control the delivery ofelectrical stimulation. In particular, in response to a command frompatient 10, external programmer 29 may activate IMD 28 to deliverelectrical stimulation or, alternatively, deactivate IMD 28 when noelectrical stimulation is desired. Patient 10 may also use the patientprogrammer to select the programs that will be used by IMD 28 to deliverelectrical stimulation. Further, patient 10 may use the patientprogrammer to make adjustments to programs, such as adjustments toamplitude, pulse width and/or pulse rate. Additionally, the clinician orpatient 10 may use a clinician or patient programmer to create or adjustschedules for delivery of electrical stimulation.

IMD 28 and external programmer 29, implemented as a clinician programmeror a patient programmer, communicate via wireless communication. In someembodiments, external programmer 29 communicates via wirelesscommunication with IMD 28 using radio frequency (RF) telemetrytechniques known in the art. The clinician programmer and patientprogrammer may communicate with one another by wireless communication,e.g., to change or update programs. Alternatively, the programmers maycommunicate via a wired connection, such as via a serial communicationcable, or via exchange of removable media, such as magnetic or opticaldisks, or memory cards.

As previously described, leads 18 and 19 may be implanted surgically orpercutaneously. When inserted percutaneously, leads 18 and 19 may beused in conjunction with an external trial stimulator (not shown) inorder to determine if permanent implantation of the electrodes and leadsis an effective treatment for the patient's pain. For example, prior toimplantation of IMD 28, patient 10 may engage in a trial period, inwhich patient 10 receives an external trial stimulator on a temporarybasis. The external trial stimulator is coupled to implanted leads via apercutaneous lead extension. As an alternative, one or more temporaryleads may be used for trial stimulation, instead of chronic leads, whichare implanted if trial stimulation is effective.

The trial neurostimulation permits a clinician to observeneurostimulation efficacy and determine whether implantation of achronic neurostimulation device is advisable. Specifically, the trialneurostimulation period may assist the clinician in selecting values fora number of programmable parameters in order to define theneurostimulation therapy delivered to patient 10. For example, theclinician may select an amplitude, which may be current- orvoltage-controlled, and pulse width for a stimulation waveform to bedelivered to patient 10, as well as a rate, i.e., frequency) deliveredto the patient. In addition, the clinician also selects particularelectrodes on a lead to be used to deliver the pulses, and thepolarities of the selected electrodes.

By stimulating nerves associated with the spermatic cord, a system inaccordance with an embodiment of the invention may substantially reduceor eliminate pelvic pain such as CTP, post vasectomy pain, genitofemoralneuralgia, and other conditions that cause long term pain in thetesticles, groin, or abdomen. Testicle removal and spermatic corddenervation procedures may result in permanent and substantial painrelief but may also cause unwanted side effects, such as loss ofsensation in the testicle and/or scrotum, loss of the cremasteric reflexwhich may cause fertility issues, and even loss of blood flow causingthe testicle to die. Therapeutic nerve blocks may also be used to treatCTP, but generally only relieve pain temporarily. Because electricalstimulation does not require severing any nerves associated with thespermatic cord and, more particularly, aims to avoid damaging nerves,the invention may provide similar or improved pain relief without theunwanted side effects.

FIG. 2 is a schematic diagram further illustrating system 2. Inparticular, system 2 is illustrated from the left side of patient 10.For purposes of illustration, only spermatic cord 15, genital nervebranch 23, femoral nerve branch 25, genitofemoral nerve 21, and testicle13 are shown. Furthermore, cuff electrode 16 is illustrated as beingwrapped around spermatic cord 15 to illustrate the different locationsat which electrodes may be implanted and to illustrate an embodiment inwhich multiple electrodes are implanted along a single spermatic cord15. Accordingly, cuff electrode 17 is shown as being wrapped aroundgenital nerve branch 23, while cuff electrode 16 is shown as beingwrapped around spermatic cord 15. Following the convention illustratedin FIG. 1, a dotted circle illustrates an example stimulation site atwhich an electrode may be implanted proximate to genitofemoral nerve 21in combination with one or more of electrodes 16 and 17. In anembodiment in which two or more electrodes are implanted along the samespermatic cord, the electrodes may form a bipolar pair that isreferenced between the two electrodes, or be individually referenced toan electrical potential associated with IMD 28. Also, in someembodiments, multiple cuffs or leads may be implanted along a singlespermatic cord 15, and each may carry multiple electrodes, e.g., in anaxial or planar array, providing still more possible electrodecombinations for selection by a physician.

FIG. 2 illustrates genital nerve branch 23 originating fromgenitofemoral nerve 21 and passing through inguinal canal 27 toinnervate testicle 13. As previously described, spermatic cord 15 joinsan external fascia layer 30 as it passes through the superficial ring ofthe inguinal canal. Genital nerve branch 23 is shown within the externalfascia 30 of spermatic cord 15. Cuff electrode 16 is wrapped aroundexternal fascia 30 of spermatic cord 15. External fascia 30 may serve toprotect genital nerve branch from being damaged when cuff electrode 16is implanted. In particular, external fascia 30 prevents cuff electrode16 from being in direct contact with genital nerve branch 23 which mayresult in a more pleasant paresthesia because electrical stimulation isdelivered to genital nerve branch 23 indirectly. Additionally, asmentioned previously, external fascia 30 may provide a buffer thatreduces the damage to genital nerve branch 23 when patient 10 moves. Forexample, external fascia 30 may act as a cushion that prevents cuffelectrode 16 from pinching, stretching, or otherwise damaging genitalnerve branch 23 as patient 10 moves.

In general, cuff electrodes 16 and 17 may be particularly advantageousbecause cuff electrodes 16 and 17 may remain in place as patient 10moves without requiring any external fixation means such as sutures oranchoring mechanisms. External fixation means may damage tissue or thenerve itself, possibly causing additional pain which may reduce theefficacy of the electrical stimulation therapy. Cuff electrodes 16 and17 include a fixation structure that at least partially wraps aroundspermatic cord 15 and genital nerve branch 23, respectively. Thefixation structure may be fabricated from a flexible biocompatiblematerial that provides a flexible interface between the electrode andthe tissue, i.e., spermatic cord 15 or genital nerve branch 23. In someembodiments, the fixation structure may be fabricated from a rigidbiocompatible material. In such cases, the fixation structure may form asplit cylinder or a “U” shape sized to fit around the spermatic cord orgenital nerve branch. Cuff electrodes 16 and 17 may generally comprise arigid cuff electrode, a self-sizing spiral cuff electrode, a half cuffelectrode, a helical electrode, a chambered electrode, and other typesof cuff electrodes that at least partially wrap around a spermatic cord.Upon enclosure of at least a portion of the spermatic cord, a cuff maybe held in a closed position by shape memory properties, sutures,interlocking tabs, surgical adhesive, crimping, or other fixationtechniques or structures.

FIGS. 3A-C are schematic diagrams illustrating an exemplary embodimentof a cuff electrode 16. Cuff electrode 17 may be similarly constructed.Cuff electrodes 16 and 17 may be any type of cuff electrode used todeliver electrical stimulation. In some embodiments, cuff electrodes 16and 17 may both comprise the same type of cuff electrode or may comprisedifferent types of cuff electrodes. In any case, cuff electrode 16 ismerely exemplary and should not be considered limiting of the inventionas broadly embodied and described in this disclosure. The purpose ofFIGS. 3A-C is to illustrate the implantation of cuff electrodes todeliver electrical stimulation to the spermatic cord and genital branchof the genitofemoral nerve.

FIG. 3A is a top view of cuff electrode 16. Cuff electrode 16 includeslead 18, fixation structure 40, a plurality of stimulation electrodes48A-C, and a plurality of electrical conductors 46 and 47 within lead18. Conductor 46 may comprise one or more supply wires 46 that deliverelectrical stimulation therapy to one or more electrodes. In the exampleof FIG. 3A, cuff electrode 16 includes three electrodes 48A, 48B, 48C.In the illustrated example, electrodes 48A-C are arranged such that amajor axis of each electrode extends laterally to the spermatic cord. Inthis manner, the length of each electrode may be wrapped about all or aportion of the circumference of the spermatic cord. The proximal end 44of lead 18 is connected to IMD 28 and fixation structure 40 is attachedto the distal end 42 of lead 18.

Cuff electrode 16 may generally include one electrode or a plurality ofelectrodes. Each of electrodes 48A-C is coupled to one of supplyconductors 46. Electrodes 118A-C may be driven together with a commonconductor or independently via separate conductors 46. When electrodes48A-C are driven by a common conductor, they may be referenced to one ormore electrodes carried by another lead or one or more electrodescarried by the IMD housing. When electrodes 48A-C are driven by separateconductors, bipolar or multipolar electrode combinations may be formedon a single lead or among two or more leads, as well as between one ormore leads and the IMD housing.

For a given bipolar pair of electrodes on a lead, one supply conductorsources stimulation energy to a first electrode and a second supplyconductor sinks stimulation energy from a second electrode, with thestimulation energy propagating across nerve tissue between the first andsecond electrodes. Hence, one electrode may form a cathode while theother forms an anode. Also, in some embodiments, multiple anodes andcathodes may be used in an electrode combination. A switch device in theIMD determines which electrodes will function as cathodes and whichelectrodes will function as anodes.

As previously described, fixation structure 40 may be fabricated from aflexible biocompatible material that provides a flexible interfacebetween the electrode and the spermatic cord genital nerve branch. Insome embodiments, fixation structure 40 may be fabricated from a rigidbiocompatible material. The rigid fixation structure may form a splitcylinder or a “U” shape sized to fit around the spermatic cord orgenital nerve branch. In any case, when implanting electrode 16, thesurgeon may elevate the spermatic cord and wrap fixation structure 40around the spermatic cord or genital nerve branch. The manner in whichthe surgeon installs the cuff electrode around the spermatic cord orgenital nerve branch depends on the type of cuff electrode. For example,if fixation structure 40 is fabricated from a shape memory alloy,fixation structure 40 may recover its shape at a fixed temperature,e.g., slightly under room temperature. By sufficiently cooling fixationstructure 40, the surgeon can easily open the cuff and position fixationstructure 40 under the spermatic cord. Because the nominal bodytemperature of the patient is above room temperature, fixation structure40 warms up and recovers its initial shape thereby closing or wrappingfixation structure 40 around the spermatic cord.

A cuff electrode may provide more direct electrical contact with a nervethan a standard ring or paddle electrode lead. However, in some cases,applying electrical stimulation directly to a nerve may result in thepatient experiencing an unpleasant sensation, such as a burningsensation. Consequently, a standard electrode implanted proximate to thetarget nerve may be advantageous because the patient may experience amore pleasant paresthesia as a result of stimulation. In addition, astandard electrode lead may also be advantageous in terms of surgicalease of implantation.

FIG. 3B is a cross sectional view of cuff electrode 16 implantedunderneath spermatic cord 15. In the illustrated example, fixationstructure 40 is flat thereby allowing the surgeon to easily positionelectrode 16 under spermatic cord 15. When fixation structure 40 isfabricated from a shape memory alloy material, such as Nitinol, thesurgeon may cool fixation structure 40 prior to positioning fixationstructure 40 to easily manipulate fixation structure 40 into the openconfiguration shown in FIG. 3B. The surgeon may then position fixationstructure under spermatic cord 15. Fixation structure 40 will recoverits initial shape, i.e., a substantially closed ring sized to fit aroundspermatic cord 15, as fixation structure warms up to its activationtemperature.

FIG. 3C is a cross sectional via of cuff electrode 16 implanted andwrapped around spermatic cord 15. More specifically, FIG. 3C illustratesthe shape of fixation structure 40 when it has returned to its initialshape in response to warming from the patient's body heat. In theillustrated example, a gap 49 exists between spermatic cord 15 andfixation structure 40. The gap may be filled with tissue or fluids andmay provide a buffer that prevents cuff electrode 16 from damagingspermatic cord 15. Alternatively, fixation structure 40 may be sized towrap around spermatic cord 15 such that there is no gap between fixationstructure 40 and spermatic cord 15. In some embodiments, fixationstructure may be deployed used superelastic properties of a shape memoryallow such as Nitinol. For example, the fixation structure may beconstrained in a flat shape either manually or with a surgical took, andthen released so that it wraps around the nerve.

FIG. 4 is a block diagram illustrating an example configuration of IMD28. IMD 28 may apply electrical stimulation to spermatic cord 14 andgenital branch 23 of the genitofemoral nerve 21 of patient 10 via cuffelectrodes 16 and 17 coupled to IMD 28 via leads 18 and 19,respectively. The configuration, type, and number of electrodesillustrated in FIG. 4 are merely exemplary. Leadless stimulatorsalternatively may be used instead of or in addition to leads 18, 19 andcuff electrodes 16, 17. A leadless stimulator does not generally includeany elongated leads, and instead carries electrodes on a housing of thestimulator or on a structure such as a fixation device extending fromthe housing.

In the example of FIG. 4, cuff electrodes 16 and 17 are electricallycoupled to a therapy delivery module 52 via leads 18 and 19,respectively. Therapy delivery module 52 may, for example, include anoutput pulse generator coupled to a power source such as a battery andcharge storage capacitor. Therapy delivery module 52 may deliverelectrical stimulation pulses to patient 10 via one or both ofelectrodes 16 and 17 under the control of a processor 54.

Processor 54 controls therapy delivery module 52 to deliver electricalstimulation according to a selected parameter set stored in memory 56.Specifically, processor 54 may control circuit 52 to deliver electricalstimulation pulses with the amplitudes and widths, and at the ratesspecified by the programs of the selected parameter set. Processor 54may also control circuit 52 to deliver each pulse according to adifferent program of the parameter set. Processor 54 may include amicroprocessor, a controller, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or any other equivalent integrated or discrete logiccircuitry, or the like.

In some embodiments, memory 50 may store parameter sets 58 that areavailable to be selected by patient 10 for delivery of electricalstimulation. Memory 50 may also store schedules 56. Memory 50 mayinclude any combination of volatile, non-volatile, fixed, removable,magnetic, optical, or solid state media, such as a random access memory(RAM), random access memory (ROM), CD-ROM, hard disk, removable magneticdisk, memory cards, non-volatile RAM (NVRAM), electrically programmableROM (EEPROM), flash memory, and the like.

IMD 28 delivers stimulation according to preprogrammed stimulationparameters and, optionally, schedules stored in memory 50. Schedules 56may define times for processor 54 to select particular parameter sets 58and control therapy delivery module to delivery therapy according tothat parameter set. A schedule 56 may cause electrical stimulation to bedelivered via electrodes 16 and 17 at respective times, which mayinclude simultaneous and/or alternate delivery. For example, stimulationmay be activated, deactivated or altered for different times of the day,such as times during which the patient is awake or sleeping, or workingor at rest. A clinician or patient may create, modify, and selectschedules 56 using external programmer 29.

IMD 28 also includes a telemetry circuit 53 that allows processor 54 tocommunicate with external programmer 29, i.e., a clinician programmer orpatient programmer. Processor 54 may receive programs to test on patient10 from external programmer 29 via telemetry circuit 52 duringprogramming by a clinician. Where IMD 28 stores parameter sets 58 inmemory 50, processor 54 may receive parameter sets 58 from externalprogrammer 29 via telemetry circuit 52 during programming by aclinician, and later receive parameter set selections made by patient 10from external programmer 29 via telemetry circuit 52. Where externalprogrammer 29 stores the parameter sets, processor 54 may receiveparameter sets selected by patient 10 from external programmer 29 viatelemetry circuit 52.

FIG. 5 is a block diagram illustrating an example patient programmer 71that allows a clinician to program electrical stimulation therapy for apatient. Patient 10 may interact with a processor 60 via a userinterface 62 in order to control delivery of electrical therapy asdescribed herein. User interface 62 may include a display and a keypad,and may also include a touch screen or peripheral pointing devices asdescribed above. Processor 60 may also provide a graphical userinterface (GUI) to facilitate interaction with patient 10, as will bedescribed in greater detail below. Processor 60 may include amicroprocessor, a controller, a DSP, an ASIC, an FPGA, discrete logiccircuitry, or the like.

Patient programmer 71 also includes a memory 64. In some embodiments,memory 64 may store parameter sets 68 that are available to be selectedby patient 10 for delivery of electrical stimulation. Memory 64 may alsostore schedules 66. Hence, parameter sets and schedules may be stored inIMD 28, patient programmer 71, or both. Patient programmer 71 alsoincludes a telemetry circuit 70 that allows processor 60 to communicatewith IMD 28, and, optionally, input/output circuitry 72 that to allowprocessor 60 to communicate with a clinician programmer.

Processor 60 may receive parameter set selections made by patient 10 viauser interface 62, and may either transmit the selection or the selectedparameter set to IMD 28 via telemetry circuitry 70 for delivery ofelectrical stimulation according to the selected parameter set. Wherepatient programmer 71 stores parameter sets 66 in memory 64, processor60 may receive parameter sets 66 from a clinician programmer viainput/output circuitry 72 during programming by a clinician. Circuitry72 may include transceivers for wireless communication, appropriateports for wired communication or communication via removable electricalmedia, or appropriate drives for communication via removable magnetic oroptical media.

FIG. 6 is a block diagram illustrating an example clinician programmer81 that allows a clinician to control delivery of electricalstimulation. A clinician may interact with a processor 80 via a userinterface 82 in order to program delivery of electrical stimulation asdescribed herein. User interface 82 may include a display and a keypad,and may also include a touch screen or peripheral pointing devices asdescribed above. Processor 80 may also provide a graphical userinterface (GUI) to facilitate interaction with a clinician, as will bedescribed in greater detail below. Processor 80 may include amicroprocessor, a controller, a DSP, an ASIC, an FPGA, discrete logiccircuitry, or the like.

Clinician programmer 81 also includes a memory 84 that stores parametersets 88 and schedules 86. Parameter sets 88 may be made available to beselected by a clinician for delivery of electrical stimulation. Memory84 may also store schedules 86 which cause electrical stimulation to bedelivered via electrodes 16 and 17 at respective times. A clinician mayprogram delivery of electrical stimulation by specifying parameter sets86. The clinician may interact with the GUI and user interface 82 inorder to specify parameter sets.

Processor 80 transmits the selected or specified parameter sets to IMD28 for delivery to patient 10 via a telemetry circuit 88. Processor 80may transmit parameter sets 86 and schedules 88 created by the clinicianto IMD 28 via telemetry circuitry 88, or to patient programmer 71 viainput/output circuitry 92. I/O circuitry 92 may include transceivers forwireless communication, appropriate ports for wired communication orcommunication via removable electrical media, or appropriate drives forcommunication via removable magnetic or optical media.

FIG. 7 is a schematic diagram illustrating an example system 100 forapplying electrical stimulation to a male patient 10 for pelvic painsuch as CTP, post vasectomy pain, genitofemoral neuralgia, and otherconditions that cause long term (chronic) pain in the testicles, groin,or abdomen. System 100 also may be useful for alleviation of pelvic forfemale patients. In the illustrated example, system 100 includeselectrodes 104 deployed on a lead extending from an IMD 108, and aleadless microstimulator 106. Electrodes 104 and leadlessmicrostimulator 106 deliver electrical stimulation to spermatic cord 15and 14, respectively, and illustrate alternative arrangementsstimulation. Hence, stimulation energy may be delivered to spermaticcords 14, 15 via any combination of cuff electrodes, axial electrodearrays, planar electrode array (e.g., on paddle lead), leadlessmicrostimulators, or other types of electrodes. As previously described,electrodes 104 and leadless microstimulator may, in some embodiments, beimplanted proximate to genitofemoral nerve 21. Following the conventionillustrated in FIGS. 1 and 2, a dotted circle illustrates an examplestimulation site at which an electrodes 104 and microstimulator 106 maybe implanted proximate to genitofemoral nerve 21.

IMD 108 controls the delivery of electrical stimulation according topreprogrammed stimulation programs, parameter sets and/or schedules. Inparticular, IMD 108 or external programmer 109 may wirelessly controlmicrostimulator 106 to deliver electrical stimulation to spermatic cord14. Alternatively, microstimulator 106 may operate autonomously or in acoordinated manner in conjunction with other microstimulators or IMD108. In the example of FIG. 7, IMD 108 is also coupled to electrodes 104via lead 102. Again, the invention is not limited to the illustratedconfiguration. In general, IMD 108 may be coupled to any number and typeof electrodes or electrical stimulators. The electrodes may also bepositioned adjacent to one or both spermatic cords 14, 15 based on theperceived pain of patient 10. However, FIG. 7 merely illustrates examplesystem 100 in which microstimulator 106 and electrodes 104 deliverbi-lateral electrical stimulation to spermatic cords 14 and 15.

In the illustrated example, microstimulator 106 is implanted adjacent tospermatic cord 14 and includes a housing and a fixation structureattached to the housing. The housing may be formed into a capsule-likeshape and may be constructed from any of a variety of biocompatiblematerials, such as titanium or stainless steel. As will be described,the housing may carry an implantable pulse generator (IPG) and,optionally, a telemetry interface to exchange (send, receive or both)control signals with other devices such as IMD 108 or externalprogrammer 109. The fixation structure on microstimulator 106 may beconstructed similar to the fixation structure of previously describedcuff electrodes 16 and 17. For example, the fixation structure onmicrostimulator 106 may be constructed of a flexible or a rigidbiocompatible material that at least partially wraps around spermaticcord 14. The fixation structure may carry one or more electrodes, i.e.,the electrodes may be integrated with the fixation structure, and thehousing may include short leads that extend from the housing to couplethe electrodes to the housing.

Alternatively, leadless microstimulator 106 may be implanted within theexternal fascia of spermatic cord 14 using a needle (not shown). Inparticular, microstimulator 106 may be implanted with a minimallyinvasive, percutaneous procedure. As an example, the needle may includea hollow cylinder and a pointed distal end for puncturing skin ofpatient 10. The needle may include the microstimulator and a fluid,e.g., saline solution, or push rod to force the microstimulator out ofthe needle. In this case, microstimulator 106 may be miniaturized inorder to be implanted using the needle. In some embodiments, a pluralityof microstimulators may be implanted within the external fascia of thespermatic cord or in tissue proximate to the genital branch of thegenitofemoral nerve. The plurality of implanted microstimulators mayapply electrical stimulation independently or on a coordinated basis.

When implanted within the external fascia of the spermatic cord,microstimulator 106 may comprise a self-contained module. The modulecomprises a housing that may carry one or more electrodes and an IPGwithin the housing. The IPG may comprise a circuit board and a powersource, such as a battery, to provide power to the circuit board andelectrodes. The circuit board may include the telemetry interface andother processing electronics. The electrodes may be pads mounted on asurface of the housing or ring electrodes that extend about the entireperiphery of the housing. In some cases, the housing itself may form anactive “can” electrode in addition to the electrodes mounted on thehousing.

Microstimulator 106 may be implanted with less invasive procedures thanother electrodes that are coupled to an IMD via a lead. For example,because microstimulator 106 wirelessly communicates with IMD 108, asurgeon does not have to tunnel a lead to IMD 108. In some embodiments,microstimulator 106 may wirelessly communicate with external programmer109. In this case, external programmer 109 may be a small,battery-powered, portable device that may accompany patient 10 throughthe day. External programmer 109 may have a simple user interface, suchas a button or keypad, and a display or lights. Patient 10 may only beable to activate and deactivate IMD 108. However, in other embodiments,external programmer 109 may include additional functionality to operatein a manner similar to a patient programmer.

In the illustrated example, ring electrodes 104 mounted on lead 102 alsomay be used to deliver electrical stimulation to spermatic cord 15. Lead102 is coupled to IMD 108 and caries electrical conductors to transmitstimulation energy from the IMD to the electrodes 104. Lead 102 may beimplanted adjacent to spermatic cord 15 as shown. However, lead 102 mayalso be implanted adjacent to genital nerve branch 23 instead of, or inaddition to, the illustrated location. Lead 102 is shown in FIG. 7carrying four electrodes, e.g., ring electrodes, although any number ofelectrodes could be used. Also, as mentioned previously, electrodes 104may be arranged in an axial array, e.g., as ring electrodes, or in atwo-dimensional planar array, e.g., in a paddle lead. Also, other typesof leads providing curved or rounded electrode arrays may be used. Atleast one conductor is included in lead 102 that electrically connectsthe proximal end of lead 102 to electrodes 104 in its distal end. IMD108 may control electrical stimulation applied by each of electrodes 104separately or control electrical stimulation applied by a group ofelectrodes 104.

In some embodiments, lead 102 may be formed to include fixationelements, such as hooks, barbs, helical structures, tissue ingrowthmechanisms, or other anchoring mechanisms, e.g., at a distal end of lead102. Fixation elements may serve to fix electrodes 104, relative tospermatic cord 15 so that electrodes 104 can provide consistentelectrical simulation. Without anchoring electrodes 104 to spermaticcord 15 or tissue proximate to spermatic cord 15, the distance betweenelectrodes 104 and spermatic cord may vary as patient 10 movesthroughout the day, reducing the efficacy of the applied electricalstimulation. However, is possible that anchoring mechanisms may damagethe spermatic cord or surrounding tissue during implantation or aspatient 10 moves.

System 100 generally operates in a similar manner to system 2 in FIG. 1to apply electrical stimulation for CTP or other pelvic pain disorders.Accordingly, external programmer 109 may comprise a clinician programmeror a patient programmer. As shown, external programmer 109 maycommunicate via wireless communication with IMD 108 In particular,external programmer 109 may control delivery of electrical stimulationby IMD 108 using telemetry techniques known in the art. Whenmicrostimulator 106 comprises a self-contained module, externalprogrammer 109 may directly communicate with microstimulator 106 viawireless communication to control delivery of electrical stimulation.

Rather than being implanted along a side of spermatic cord 15, in adirection substantially parallel to the path of the spermatic cord,electrodes 104 of lead 102 may be implanted substantially perpendicularto the spermatic cord. Implanting electrodes 104 perpendicular tospermatic cord 15 may provide certain advantages. For example, whenimplanted perpendicular, electrodes 104 may more effectively applyelectrical stimulation to a point along spermatic cord 15 instead ofapplying electrical stimulation along a length or portion of thespermatic cord. Patient 10 may experience a more complete relief of painor fewer unwanted side effects as a result of applying electricalstimulation in this manner. The invention is not limited to theillustrated embodiments. Instead, electrodes 104 may be implanted at anyorientation with respect to spermatic cord 15.

FIG. 8 is a schematic diagram further illustrating example system 100.In particular, system 100 is illustrated from the left side of a malepatient 10 in FIG. 8. For purposes of illustration, only spermatic cord15, genital nerve branch 23, femoral nerve branch 25, genitofemoralnerve 21, inguinal canal 27, and testicle 13 are shown. Again,genitofemoral nerve 21 originates from the L1 and L2 nerves in thelumbar region and divides into femoral branch 25 and genital branch 23.The dotted circle indicates an example stimulation site at which anelectrode may be implanted to apply electrical stimulation togenitofemoral nerve 21. Femoral branch 25 supplies the skin over thefemoral triangle (not shown) and communicates with the intermediatecutaneous nerve (not shown) of the thigh.

In general, electrical stimulation is applied to spermatic cord 15through electrodes 104 of lead 102 implanted adjacent to spermatic cord15. Electrodes 104 apply electrical stimulation to spermatic cord 15under control of IMD 108. Lead 102 carries electrodes 104 and coupleselectrodes 104 to IMD 108. In particular, at least one electricalconductor is included in lead 102 that electrically connects electrodes104 to IMD 108. Electrodes 104 may comprise four electrodes, e.g., ringelectrodes, although the invention is not so limited. Electrodes 104 maycomprise any number and type of electrodes. In some embodiments, asmentioned above, lead 102 may include fixation elements, such as hooks,barbs, helical structures, tissue ingrowth mechanisms, or otheranchoring mechanisms that aid in securing lead 102 to spermatic cord 15or tissue proximate to spermatic cord 15. Securing lead 102 to spermaticcord 15 or to tissue proximate to spermatic cord 15 may prevent lead 102from moving relative to spermatic cord 15.

IMD 108 is programmed to deliver electrical stimulation appropriate forCTP, post vasectomy pain, genitofemoral neuralgia, and other conditionsthat cause long term (chronic) pain in the testicles, groin, or abdomen.IMD 108 may control electrical stimulation applied by each of electrodes104 independently. Alternatively, IMD 108 may control electricalstimulation applied by a group of electrodes 104, and may selectdifferent combinations of electrodes 104 in bipolar or multi-polararrangements to identify a particular combination that is most effectivein producing desired parasthesia. Again, IMD 108 may control delivery ofelectrical stimulation according to parameter sets and/or schedulesprogrammed in internal memory.

Although FIG. 8 illustrates lead 102 implanted adjacent to spermaticcord 15 below inguinal canal 27, lead 102 may be implanted adjacent togenital nerve branch 23 above inguinal canal 27. In this case,electrodes 104 may apply electrical stimulation to genital nerve branch23 more directly. In addition, applying electrical stimulation togenital nerve branch 23 at a location further upstream may cause patient10 to experience a larger area of paresthesia in response to electricalstimulation. In both male and female patients, stimulation may beapplied close or below the inguinal canal 27.

FIGS. 9A-C show exemplary electrical leads with fixation elements tosecure the lead within a patient. As shown in FIG. 9A, lead 110 includeslead body 112, tines 116A-D (collectively tines 116) and electrodes114A-D (collectively electrodes 114). Lead 110 may be a standard leadthat includes all four tines 116 close to electrodes 114. Lead 110 maybe implemented with any number of electrodes or tines. When implantinglead 110, having tines 116 close to electrodes 114 may be beneficial byallowing less movement of electrodes 114 with respect to the spermaticcord.

Electrodes 114 are more effective in delivering electrical stimulationwhen the electrodes are located close to the genital nerve branchspermatic cord. If electrodes 114 migrated away from the spermatic cord,due to movement of the patient throughout the day, for example, theefficacy of the stimulation may decrease. Therefore, tines 116 locatedclose to electrodes 114 may be beneficial to therapy efficacy.

FIG. 9B illustrates a lead 120 which includes lead body 122, tines 126,and electrodes 124A-D (collectively electrodes 124). Lead 120 may be astandard lead that includes tines 126 located at the distal end of leadbody 122. Lead 120 may be implemented with any number of electrodes ortines. Electrodes 124 may be located close to or a distance away fromtines 126. When electrodes 124 are close to tines 126, implanting lead120 may allow less movement of electrodes 124 with respect to thespermatic cord. Consequently, the intensity of electrical stimulationdelivered to the spermatic cord may not vary and cause the patient toexperience different levels of paresthesia.

When electrodes 124 are located a distance away from tines 126,implanting lead 102 may allow electrodes 124 to reach further away fromthe anchoring site. For example, when lead 102 delivers electricalstimulation to a genital branch of the genitofemoral nerve above theinguinal canal, i.e., before the genital nerve branch joins thespermatic cord, tines may be anchored to tissue a distance away from thegenital nerve branch while leads may be located proximate to the genitalnerve branch. Securing tines 126 to genital nerve branch is undesirablebecause the nerve may be damaged in the process. Thus, lead 120 may bebeneficial by preventing unwanted nerve damage during the implantationprocess.

FIG. 10 is a schematic diagram further illustrating example system 100.In particular, system 100 is illustrated from the right side of a malepatient 10. For purposes of illustration, only spermatic cord 14,genital nerve branch 22, femoral nerve branch 24, genitofemoral nerve20, inguinal canal 26, and testicle 12 are shown. As previouslydescribed, spermatic cord 14 includes various layers and structures. Forexample, as spermatic cord 14 passes through inguinal canal 26, it joinsthe cremasteric layer of muscle and fascia responsible for thecremasteric reflex. Additionally, spermatic cord 14 picks up an externalfascia layer 32 as it exits inguinal canal 26 through the superficialring. Accordingly, genital branch 22 is shown within the external fascia32 of spermatic cord 14.

Microstimulator 106 applies electrical stimulation to spermatic cord 14under control of IMD 108 or external programmer 109. As shown, IMD 108or external programmer 109 may wirelessly control microstimulator 106 todelivery electrical stimulation. Microelectrode 106 includes a housing107 and a fixation structure 105, such as a cuff, attached to housing107. Housing 107 may be formed into a capsule-like shape and may beconstructed from any of a variety of biocompatible materials, such astitanium. Housing 107 may carry an IPG and a telemetry interface toreceive control signals from IMD 108. Fixation structure 105 wraps atleast partially around spermatic cord 14 to secure microstimulator 106in place. Accordingly, fixation structure may operate and be constructedsimilar to the fixation structure of previously described cuffelectrodes 16 and 17. Fixation structure 105 may carry one or moreelectrodes coupled to housing 107 via short leads (not shown). In someembodiments, housing 107 may form an active “can” electrode.

The invention is not limited to the illustrated configuration. Forexample, microstimulator 106 may also be implanted to deliver electricalstimulation to genital nerve branch 22 above inguinal canal 26. In thiscase, fixation structure 105 wraps at least partially around genitalnerve branch 22. When applying electrical stimulation to genital nervebranch 22 before it joins spermatic cord 14, microstimulator 106 may bebeneficial because it does not require fixation elements to secure it inplace. In addition, in some embodiments, a microstimulator may implantedto deliver electrical stimulation at both locations in a coordinatedmanner or independently of each other. In further embodiments, amicrostimulator 106 may also be implanted in proximate to genitofemoralnerve 20. Microstimulator 106 may be implanted proximate togenitofemoral nerve 20 using techniques similar to implantingmicrostimulator proximate to genital nerve branch 22. The dotted circlearound genitofemoral nerve 20 indicates an example site at whichmicrostimulator may be implanted.

FIGS. 11A-C are enlarged schematic diagrams showing microstimulator 106.In particular, FIG. 11A is an enlarged top view of microstimulator 106including housing 107, circuit board 130, power supply 132, fixationstructure 105, and electrodes 108A-C (collectively electrodes 108).Housing 107 may have a rounded, capsule-like shape, and a smooth,atraumatic surface formed of one or more biocompatible materials, suchas titanium, stainless steel, epoxy, or polyvinylchloride. However, theinvention is not so limited. Instead, housing 107 may have a shape thatis compatible with the anatomy at the implant site, i.e., the spermaticcord or the genital nerve branch before it joins the spermatic cord. Insome embodiments, the leadless microstimulator may have a capsule shapewith a diameter of approximately less than or equal to 2 cm and a lengthof less than or equal to approximately 5 cm.

Fixation structure 105 may be constructed of a flexible or rigidbiocompatible material that at least partially wraps around thespermatic cord or genital nerve branch, e.g., like a cuff. For example,fixation structure 105 may be fabricated from a shape memory alloy thathas the capacity to recover a memorized shape when deformed at a certaintemperature and then heated at a higher temperature or vice versa. Inthis case, the memorized shape may be a split cylinder or asubstantially closed cylinder with a diameter sized to wrap around thespermatic nerve or genital nerve branch.

FIG. 11A illustrates fixation structure 105 in a deformed, generallyopen state that enables a surgeon to easily position slipmicrostimulator 106 underneath the spermatic cord. However, afterpositioning microstimulator 106 beneath the spermatic cord, the bodytemperature of the patient causes fixation structure 105 to recover itsmemorized shape, i.e., a split cylinder. Therefore, fixation structure105 may be beneficial by reducing trauma during surgical implantationprocedures.

Fixation structure 105 also carries one or more electrodes 108.Electrodes 108 may be driven together or independently. Electrodes 108may be integrated with fixation structure 105 or, alternatively housing107 may include short leads (not shown) that extend from housing 107 tocouple electrodes 108 to housing 107.

Circuit board 130 may include a processor, memory, pulse generatorcircuitry to generate electrical pulses delivered by 108, and telemetrycircuitry for wireless telemetry with IMD 108, external programmer 109,or both. As an example, the memory may store stimulation parameters,e.g., electrode polarity, pulse width, pulse rate, and amplitude. Memorymay also may store schedules which define times for the processor toselect particular parameters. A schedule may cause electricalstimulation to be delivered at respective times. In this manner, theprocessor may control the pulse generator circuitry generate electricalstimulation pulses in accordance with the selected parameters andschedule.

Microstimulator 106 may also operate under control from an externalprogrammer, so that a physician or patient may activate, deactivateand/or modify stimulation delivered to the patient on a selective basis.Power source 132 supplies operating power to circuit board 130 and maytake the form of a small rechargeable or non-rechargeable battery.Different types of batteries or different battery sizes may be used. Topromote longevity, power source 132 may be rechargeable via induction orother means.

FIG. 11B illustrates a cross sectional view of microstimulator 106implanted underneath spermatic cord 14. In the illustrated example,fixation structure 105 is flat, thereby allowing the surgeon to easilyposition microelectrode 106 underneath spermatic cord 14. Whenfabricated from an shape memory alloy, the body temperature of patient10 may heat fixation structure 105 above the recovery shape temperature.

FIG. 11C is a cross sectional view of microelectrode 106 with fixationsstructure 105 wrapped substantially around spermatic cord 14. Forexample, as fixation structure 105 is warmed above its recovery shapetemperature, fixation structure 105 recovers its initial shape, i.e., asubstantially closed cylinder or ring. As shown in FIG. 11C, in someembodiments, fixation structure 105 may not close completely. However,fixation structure 105 may at least wrap partially around spermatic cord14, or the genitofemoral nerve or genital nerve branch in order tosecure microstimulator 106 to the nerve site. Removing microelectrode106 may be easier when fixation structure 105 does not completely wraparound spermatic cord 14 because the gap between the ends of fixationstructure 105 may provide an area to insert a tool that aids in removal.In alternative embodiments, fixation structure 105 may wrap completelyaround spermatic cord 14.

In the illustrated example, a gap 109 exists between spermatic cord 14and fixation structure 105. Gap 109 may be filled with tissue or fluidsand may provide a buffer that prevents microstimulator 106 from damagingspermatic cord 14. Alternatively, fixation structure 105 may be sized towrap around spermatic cord 14 such that there is no gap between fixationstructure 105 and spermatic cord 14.

FIG. 12 is cross-sectional view of a microstimulator 140 implantedwithin, for example, spermatic cord 14. Housing 142 of microstimulator140 is embedded in the external fascia 32 of spermatic cord 14 andincludes circuit board 144, power source 146, and electrodes 148 and149. Housing 142 is in the shape of a rounded capsule and includes asmooth surface. The only structure extending from housing 142 areelectrodes 148 and 149. Electrodes 148 and 149 may protrude slightlyfrom housing 142 or, alternatively, may be integrated into housing 142to apply electrical stimulation to external fascia 32. Microstimulator140 rests in wall cavity 150 formed within external fascia 32. Aspreviously described, microstimulator 140 may have a cylindrical shapewith a diameter of less than or equal to approximately 2 cm and a lengthof less than or equal to approximately 5 cm.

Circuit board 144, power source 146, and electrodes 148 and 149 may besimilar to respective circuit board 130, power source 132, andelectrodes 108 of FIGS. 11A-C. Differences between these components ofeach embodiment may relate to the size or shape of each component.Therefore, electrodes 148 and 149 apply electrical stimulation undercontrol of circuit board 144. Power source supplies operating power tocircuit board 144. Circuit board 144 may select may select stimulationparameters and cause electrodes 148 and 149 to apply electrical pulseswith the selected parameters according to schedules stored in memory.Circuit board 140 receives control signals from IMD 108, externalprogrammer 109, or both by wireless telemetry. In some embodiments, oneof electrodes 148 and 148 may comprise a sensor or microstimulator 140may additionally include a sensor that detects a physiologicalparameter. In such embodiments, the sensor may sense a change in aphysiological parameter. Processing electronics on circuit board 144detects the change and causes electrodes to apply electrical stimulationin response to the change.

Implanting microstimulator 140 within external fascia 32 of spermaticcord 14 may be a simple method for securing electrodes 148 and 149.Microstimulator 140 may also be implanted in tissue proximate to genitalnerve branch 22 or implanted in tissue proximate to genitofemoral nerve20. In some embodiments, a plurality of microstimulators similar tomicrostimulator 140 may be implanted and apply electrical stimulation tospermatic cord 14 in a coordinated manner or in a manner independent ofeach other.

FIG. 13 is a schematic diagram illustrating implantation ofmicrostimulator 140 within the spermatic cord 14. Microstimulator 140may be implanted through endoscopic, laparoscopic, or similar minimallyinvasive techniques. A surgeon may make a small inguinal incision inpatient 10 and guides microstimulator 140 within needle 152 to spermaticcord 14. Needle 152 may be constructed of a metal alloy and comprise ahollow cylinder and a pointed distal end for puncturing the skin ofpatient 10. Needle 152 includes microstimulator 140 and a fluid or pushrod to force microstimulator 140 out of the needle. An exemplary fluidmay be saline or other biocompatible fluid.

Once needle 152 in positioned at the appropriate location with respectto spermatic cord 14, the surgeon may force microstimulator 140 intoplace. Removing needle 152 from spermatic cord 14 allows the externalfascia of spermatic cord 14 to close and surround microstimulator 140.When implanting microstimulator 140, the external fascia should not bebreached in order to prevent other structures within spermatic cord 14,such as the genital nerve branch, ductus deferens, lymph vessels,pampiniform plexus of veins which become the testicular vein, andtesticular artery, from being damaged.

In other embodiments, microstimulator 140 may be implanted through moreinvasive procedures which expose spermatic cord 14. As previouslydescribed, multiple microstimulators may be implanted with spermaticcord 14 to apply electrical stimulation to a larger area.Microstimulator 140 may also be implanted within tissue proximate to thegenital branch of the genitofemoral nerve.

FIG. 14 is a functional block diagram illustrating various components ofan example microstimulator 106 (FIG. 7) or microstimulator 140 (FIG.12). In the example of FIG. 14, microstimulator 140 includes a processor160, memory 162, pulse generator circuitry 164, telemetry interface 168,power source 166 and electrodes 165. Pulse generator circuitry 164 maybe carried on a circuit board, along with processor 160, memory 162, andtelemetry interface 168. Memory 162 may store instructions for executionby processor 160, stimulation parameters, e.g., electrode polarity,pulse width, pulse rate, and amplitude, and schedules for deliveringelectrical stimulation. Memory 162 may include separate memories forstoring instructions, stimulation parameter sets, and schedules. Memory162 may comprise any form of computer-readable media such as magnetic oroptical tape or disks, solid state volatile or non-volatile memory,including random access memory (RAM), read only memory (ROM),electronically programmable memory (EPROM or EEPROM), or flash memory.

Processor 160 controls pulse generator circuitry 164 to deliverelectrical stimulation via electrodes 165. Electrodes 165 may compriseany number and type of electrodes previously described, i.e., electrodes108 (FIG. 7) and electrodes 148 and 149 (FIG. 12). An exemplary range ofstimulation pulse parameters likely to be effective in treating, postvasectomy pain, genitofemoral neuralgia, and other conditions that causelong term pain in the testicles, groin, or abdomen when applied to thespermatic cord or genital nerve branch are as follows: pulse widthsbetween approximately 10 and 5000 microseconds, more preferably betweenapproximately 100 and 1000 microseconds and still more preferablybetween 180 and 450 microseconds; voltage amplitudes betweenapproximately 0.1 and 50 volts, more preferably between approximately0.5 and 20 volts and still more preferably between approximately 1 and10 volts; and frequencies between approximately 0.5 and 500 hertz, morepreferably between approximately 10 and 250 hertz and still morepreferably between approximately 50 and 150 hertz. The pulses may bealternating current (ac) pulses or direct current (dc) pulses, and maybe mono-phasic, bi-phasic, or multi-phasic in various embodiments. Inaddition, multiple patterns of pulses may be interleaved with oneanother to delivery different stimulation programs to the patient on asubstantially concurrent basis.

Processor 160 also controls telemetry interface 168 to receiveinformation from IMD 108, external programmer 109, or both. Telemetryinterface 168 may communicate via wireless telemetry, e.g., RFcommunication, on a continuous basis, at periodic intervals, or uponrequest from the implantable stimulator or programmer. Processor 160 mayinclude a single or multiple processors that are realized bymicroprocessors, Application-Specific Integrated Circuits (ASIC),Field-Programmable Gate Arrays (FPGA), or other equivalent integrated ordiscrete logic circuitry.

Power source 166 delivers operating power to the components of theimplantable microstimulator. As mentioned previously, power source 166may include a small rechargeable or non-rechargeable battery and a powergeneration circuit to produce the operating power.

FIG. 15 is a flow chart illustrating a technique for applying electricalstimulation to a spermatic cord of a patient using an implantableelectrode. Any of the previously described electrodes, i.e., cuffelectrodes 16 and 17 (FIG. 1), electrodes 104 carried by lead 102 (FIG.7), microstimulator 106 (FIG. 7), and microstimulator 140 (FIG. 12), maybe implanted in accordance with the steps of the illustrated flow chart.The flow of events begins with the surgical procedure for implanting theelectrode. The surgical procedure for exposing the spermatic cord forlead placement is well defined and may be used. Specifically, thesurgeon makes an inguinal incision (170) as used for standard spermaticdenervation or hernia repair.

The surgeon identifies the spermatic cord (172) and implants anelectrode adjacent to the spermatic cord (174). When implanting a cuffelectrode, the surgeon may elevate the spermatic cord using a primrosering and wrap the cuff electrode around the spermatic cord. If thefixation structure of the spermatic cord is formed from a shape memoryalloy, the body temperature of the patient may cause the fixationstructure to recover its initial shape, i.e., a substantially closedcylinder or ring shape sized to fit around the spermatic cord. In anycase, the cuff electrode may wrap at least partially around thespermatic cord thereby securing the cuff electrode to the spermaticcord.

When implanting lead 102 carrying electrodes 104, fixation elements suchas hooks, barbs, helical structures, tissue ingrowth mechanisms, orother anchoring mechanisms may secure lead 102 to the spermatic cord ortissue proximate to the spermatic cord. Leads carrying electrodes mayprovide distinct advantages due to the number of electrodes available toapply electrical stimulation. For example, leads are available thatcarry eight, sixteen, or more electrodes which can be used to applyelectrical stimulation in various groups or independently of each other.Further, because the electrodes may be positioned along a substantiallength of the lead, the electrodes may apply electrical stimulationalong a larger area of the spermatic cord.

The surgeon may implant microstimulator 106 similar to cuff electrodes16 and 17 because the fixation structure of microstimulator 106 mayoperate in the same manner as the fixation structure of cuff electrodes16 and 17. In contrast, the surgeon may implant microstimulator 140within the external fascia of the spermatic cord using a needle. Theneedle may comprise a hollow cylinder and a pointed distal end forpuncturing the skin of the patient and a fluid to force microstimulator140 out of the needle. Accordingly, the surgeon may not need to make aninguinal incision when implanting microstimulator 140 within theexternal fascia of the spermatic cord. Rather, once the needle ispositioned at the appropriate location with respect to the spermaticcord, the surgeon forces microstimulator 140 into place by depressingthe plunger of the needle thereby forcing the fluid and microstimulatorout of the needle.

Removing the needle from the spermatic cord allows the external fasciaof the spermatic cord to close and surround microstimulator 140.Consequently, microstimulator 140 may be implanted with a minimallyinvasive surgical procedure. Additionally, in some embodiments, thesurgeon may implant a plurality of microstimulators along the spermaticcord. The microstimulators may provide electrical stimulationindependently or on a coordinated basis.

Although the implantation techniques have been described with respect tothe spermatic cord, the implantation techniques may also be used toimplant electrodes adjacent to the genital branch of the genitofemoralnerve. In particular, the surgeon may implant the electrode adjacent tothe genital nerve branch before it joins the spermatic cord. Implantingan electrode adjacent to the genital nerve branch in this manner mayprovide paresthesia to a larger area of the patient because electricalstimulation is applied upstream of the spermatic cord.

In any case, after implanting the electrode, the surgeon may create asubcutaneous pocket in the abdomen of the patient (176) and implant anIMD, such as IMD 28 (FIG. 1) or IMD 108 (FIG. 7), within thesubcutaneous pocket (178). In some embodiments, the IMD may beminiaturized and implanted within the scrotum of the patient. Thesurgeon may then tunnel the electrode lead through the patient to theimplantation site and connect the lead to the implanted electrode(s)(180). Notably, microstimulators 106 and 140 may wirelessly communicatewith external programmer 109 to receive control signals and, thus, notrequire an IMD.

When the surgical implantation procedure is complete, the implantedelectrodes may apply electrical stimulation to deliver therapy (182) thespermatic cord or, alternatively, the genital nerve branch. Applyingelectrical stimulation to the spermatic cord may block pain signals fromthe testicles and the associated scrotal area from reach the centralnervous system. The pain experienced by the patient may be uni-lateralor bi-lateral. Consequently, electrodes may be implanted adjacent to oneor both spermatic cords of a patient. The pain experienced by thepatient may also be constant or intermittent, or spontaneous orexacerbated by physical activities and pressure. Thus, the implantedelectrodes may apply electrical stimulation on demand, such as inresponse to a control signal received from a patient or clinicianprogrammer, or in accordance with preprogrammed cycles or schedules.

Electrical stimulation of the genitofemoral nerve or the genital nervebranch may provide may provide substantial relief of pelvic painexperienced by male and female patients, including urogenital pain orother forms of pelvic pain. In male patients, for example, electricalstimulation of the genitofemoral nerve or the genital nerve branch(directly or via the spermatic cord) may relieve a variety of pelvicpain conditions such as chronic testicular pain (CTP), post vasectomypain, genitofemoral neuralgia, and other conditions that cause long term(chronic) pain in the testicles, groin, or abdomen. For female patients,electrical stimulation of the genitofemoral nerve or the genital nervebranch may alleviate a variety of pelvic pain conditions such as painresulting from surgical procedures, vulvodynia, interstitial cystitis(painful bladder syndrome), adhesions, endometriosis, and pelviccongestion. Accordingly, although the invention has been primarilydescribed with respect to male patients, the invention is not so limitedand may be readily applied to female patients for similar relief of painsymptoms.

Many embodiments of the invention have been described. Variousmodifications may be made without departing from the scope of theclaims. These and other embodiments are within the scope of thefollowing claims.

1. A system comprising: an implantable stimulation device that generateselectrical stimulation selected to alleviate pelvic pain; an electrodecoupled to the implantable stimulation device, wherein the electrode ispositioned proximate to a genital nerve branch of a genitofemoral nerveof a patient at a point after the genitofemoral nerve has branched toform the genital nerve branch and a femoral nerve branch; and acomputer-readable storage medium comprising instructions that, whenexecuted, cause the implantable stimulation device to apply theelectrical stimulation to the genital nerve branch via the electrode. 2.The system of claim 1, wherein the patient is a male patient, andwherein the computer-readable storage medium comprises instructionsthat, when executed, cause the implantable stimulation device to applythe electrical stimulation to the genital nerve branch via a spermaticcord of the patient.
 3. The system of claim 1, wherein the patient is amale patient, and wherein the computer-readable storage medium comprisesinstructions that, when executed, cause the implantable stimulationdevice to apply the electrical stimulation to the genital nerve branchat a point on a side of an inguinal canal of the patient opposite aspermatic cord of the patient.
 4. The system of claim 1, wherein thepatient is a male patient, and wherein the computer-readable storagemedium comprises instructions that, when executed, cause the implantablestimulation device to apply the electrical stimulation to the genitalnerve branch at a point on a side of an inguinal canal of the patientadjacent a spermatic cord of the patient.
 5. The system of claim 1,wherein the genital nerve branch of the genitofemoral nerve comprises afirst genital nerve branch, wherein the system further comprises asecond electrode positioned proximate to a second genital nerve branchof a second genitofemoral nerve of the patient at a point after thesecond genitofemoral nerve has branched to form the second genital nervebranch and a second femoral nerve branch, and wherein thecomputer-readable storage medium further comprises instructions that,when executed, cause the implantable stimulation device to applyelectrical stimulation to the second genital nerve branch via the secondelectrode.
 6. The system of claim 5, wherein the patient is a malepatient, wherein the computer-readable storage medium comprisesinstructions that, when executed, cause the implantable stimulationdevice to apply the electrical stimulation to the first genital nervebranch via a first spermatic cord of the patient, and wherein thecomputer-readable storage medium comprises instructions that, whenexecuted, cause the implantable stimulation device to apply theelectrical stimulation to the second genital nerve branch via a secondspermatic cord of the patient.
 7. The system of claim 5, wherein thepatient is a male patient, wherein the computer-readable storage mediumcomprises instructions that, when executed, cause the implantablestimulation device to apply the electrical stimulation to the firstgenital nerve branch at a point on a side of a first inguinal canal thatis opposite a first spermatic cord of the patient, and wherein thecomputer-readable storage medium comprises instructions that, whenexecuted, cause the implantable stimulation device to apply electricalstimulation to the second genital nerve branch at a point on a side of asecond inguinal canal that is opposite a second spermatic cord of thepatient.
 8. The system of claim 5, wherein the patient is a malepatient, wherein the computer-readable storage medium comprisesinstructions that, when executed, cause the implantable stimulationdevice to apply the electrical stimulation to the first genital nervebranch at a point on a side of a first inguinal canal that is adjacentto a first spermatic cord of the patient, and wherein thecomputer-readable storage medium comprises instructions that, whenexecuted, cause the implantable stimulation device to apply theelectrical stimulation to the second genital nerve branch at a point ona side of a second inguinal canal that is adjacent to a second spermaticcord of the patient.
 9. The system of claim 1, wherein the pelvic painincludes at least one of chronic testicular pain, post vasectomy pain,genitofemoral neuralgia, vulvodynia, and interstitial cystitis.
 10. Thesystem of claim 1, wherein the patient is a male patient, and whereinthe electrode at least partially engages a portion of a spermatic cordof the patient.
 11. The system of claim 10, wherein the electrodeincludes at least one of a cuff electrode, a ring electrode, a planarelectrode and an electrode on a leadless stimulator.
 12. The system ofclaim 10, wherein the electrode includes a cuff electrode including acuff-like fixation structure and one or more electrodes.
 13. The systemof claim 12, further comprising an implantable medical lead coupled tothe implantable stimulation device, wherein the cuff electrode ismounted on the implantable medical lead.
 14. The system of claim 12,wherein the implantable stimulation device includes a leadlessstimulator, and wherein the cuff electrode is mounted on the leadlessstimulator.
 15. The system of claim 14, wherein the patient is a malepatient, and wherein the fixation structure is flexible and at leastpartially conformable to the spermatic cord.
 16. The system of claim 1,wherein the implantable stimulation device includes a leadlessstimulator sized for at least partial implantation within a facia of aspermatic cord of the patient.
 17. The system of claim 1, wherein thegenital nerve branch of the genitofemoral nerve comprises a firstgenital nerve branch, wherein the system further comprises a secondelectrode positioned proximate to a second genital nerve branch of asecond genitofemoral nerve of the patient at a point after the secondgenitofemoral nerve has branched to form the second genital nerve branchand a second femoral nerve branch, wherein the computer-readable storagemedium further comprises instructions that, when executed, cause theimplantable stimulation device to apply the electrical stimulation tothe first genital nerve branch at a point prior to the first genitalnerve branch entering a first inguinal canal of the patient, and toapply the electrical stimulation to the second genital nerve branch at apoint after the second genital nerve branch exits a second inguinalcanal of the patient.
 18. A system comprising: means for applyingelectrical stimulation, which is selected to alleviate pelvic pain, toat least a portion of a first genitofemoral nerve of a patient at apoint prior to the first genitofemoral nerve entering a first inguinalcanal of the patient; and means for applying electrical stimulation,which is selected to alleviate pelvic pain, to at least a portion of asecond genitofemoral nerve of the patient at a point after the secondgenitofemoral nerve exits a second inguinal canal of the patient. 19.The system of claim 18, wherein the patient is a male patient, andwherein the means for applying the electrical stimulation to at leastthe portion of the first genitofemoral nerve comprises means forapplying the electrical stimulation to a genital nerve branch of thefirst genitofemoral nerve on a side of the first inguinal canal of thepatient that is opposite a first spermatic cord of the patient.
 20. Thesystem of claim 18, wherein the patient is a male patient, and whereinthe means for applying the electrical stimulation to at least theportion of the second genitofemoral nerve comprises applying theelectrical stimulation to a genital nerve branch of the secondgenitofemoral nerve on a side of the second inguinal canal of thepatient that is adjacent a second spermatic cord of the patient.
 21. Thesystem of claim 18, wherein the pelvic pain includes at least one ofchronic testicular pain, post vasectomy pain, genitofemoral neuralgia,vulvodynia, and interstitial cystitis.
 22. The system of claim 18,wherein the patient is a male patient, and wherein the system furthercomprises an electrode configured to at least partially engage a portionof a spermatic cord of the patient.
 23. The system of claim 22, whereinthe electrode includes at least one of a cuff electrode, a ringelectrode, a planar electrode and an electrode on a leadless stimulator.24. The system of claim 22, wherein the electrode includes a cuffelectrode including a cuff-like fixation structure and one or moreelectrodes.
 25. The system of claim 24, wherein the cuff electrode ismounted on an implanted medical lead.
 26. The system of claim 24,wherein the cuff electrode is mounted on the leadless stimulator. 27.The system of claim 26, and wherein the cuff-like fixation structure isflexible and at least partially conformable to the spermatic cord.
 28. Acomputer-readable storage medium comprising instructions that, whenexecuted, cause an implantable stimulation device to: apply electricalstimulation, which is selected to alleviate pelvic pain, to a genitalnerve branch of a genitofemoral nerve of a patient via an electrode thatis positioned proximate to the genital nerve branch at a point after thegenitofemoral nerve has branched to form the genital nerve branch and afemoral nerve branch.